1. Field
The present disclosure relates to systems and methods for estimating the amount of treatment a patient received during a previous myopic or mixed astigmatism excimer laser refractive surgery, and more particularly, to utilizing this estimation to determine an accurate intraocular lens (IOL) power for subsequent phacoemulsification cataract surgery for the patient.
2. Related Art
The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
It is well known that using standard equations to determine the intraocular lens (IOL) power for routine phacoemulsification cataract surgery in patients with high expectations who have had previous myopic excimer laser photorefractive keratectomy (PRK) or LASIK corneal surgery often leads to unwanted postoperative hyperopia.1-8 This occurs because the actual central keratometric power is overestimated with current manual or topographic keratometers, the standard lens formulas do not take into account the altered anterior/posterior corneal curvature relationship after excimer ablation, and the effective lens position is erroneously assumed to be more anterior for the Hoffer, SRK/T (Sanders, Retzlaff, Kraff), and Holladay formulas, and to a lesser extent for the Haigis formula.9-16 Numerous theoretic and empiric approaches to solve this clinical dilemma have been proposed.3,9-11, 14, 16-41 Some of these methods require pre-refractive surgery keratometry, surgical change in spherical equivalent (SE), or excimer laser data that, for most patients, will not be readily available in the future. Therefore, newer formulas or methods that only require information readily obtained at the actual cataract consultation visit are clinically important for this group of patients.